National and Subnational estimates for the United States of America

Identifying changes in the reproduction number, rate of spread, and doubling time during the course of the COVID-19 outbreak whilst accounting for potential biases due to delays in case reporting both nationally and subnationally in the United States of America. These results are impacted by changes in testing effort, increases and decreases in testing effort will increase and decrease reproduction number estimates respectively (see Methods for further explanation).

Table of Contents


Using data available up to the: 2020-05-24

Note that it takes time for infection to cause symptoms, to get tested for SARS-CoV-2 infection, for a positive test to return and ultimately to enter the case data presented here. In other words, today’s case data are only informative of new infections about two weeks ago. This is reflected in the plots below, which are by date of infection.

Expected daily confirmed cases by region


Figure 1: The results of the latest reproduction number estimates (based on estimated confirmed cases with a date of infection on the 2020-05-14) in the United States of America, stratified by state, can be summarised by whether confirmed cases are likely increasing or decreasing. This represents the strength of the evidence that the reproduction number in each region is greater than or less than 1, respectively (see the methods for details). Regions with fewer than 40 confirmed cases reported on a single day are not included in the analysis (light grey).

National summary

Summary (estimates as of the 2020-05-14)

Table 1: Latest estimates (as of the 2020-05-14) of the number of confirmed cases by date of infection, the expected change in daily confirmed cases, the effective reproduction number, the doubling time (when negative this corresponds to the halving time), and the adjusted R-squared of the exponential fit. The mean and 90% credible interval is shown for each numeric estimate.
Estimate
New confirmed cases by infection date 25830 (22966 – 28914)
Expected change in daily cases Increasing
Effective reproduction no. 1.1 (1 – 1.1)
Doubling/halving time (days) 34 (22 – 72)
Adjusted R-squared 0.89 (0.82 – 0.97)

Confirmed cases, their estimated date of infection, and time-varying reproduction number estimates


Figure 2: A.) Confirmed cases by date of report (bars) and their estimated date of infection. B.) Time-varying estimate of the effective reproduction number. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Estimates from existing data are shown up to the 2020-05-14 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The vertical dashed line indicates the date of report generation.

Time-varying rate of growth and doubling time


Figure 3: A.) Time-varying estimate of the rate of growth, B.) Time-varying estimate of the doubling time in days (when negative this corresponds to the halving time), C.) The adjusted R-squared estimates indicating the goodness of fit of the exponential regression model (with values closer to 1 indicating a better fit). Estimates from existing data are shown up to the 2020-05-14. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.

Regional Breakdown

Data availability

Limitations

Summary of latest reproduction number and confirmed case count estimates by date of infection


Figure 4: Confirmed cases with date of infection on the 2020-05-14 and the time-varying estimate of the effective reproduction number (light bar = 90% credible interval; dark bar = the 50% credible interval.). Regions are ordered by the number of expected daily confirmed cases and shaded based on the expected change in daily confirmedcases. The horizontal dotted line indicates the target value of 1 for the effective reproduction no. required for control and a single case required for elimination.

Reproduction numbers over time in the six regions expected to have the most new confirmed cases


Figure 5: Time-varying estimate of the effective reproduction number (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates from existing data are shown up to the 2020-05-14 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The horizontal dotted line indicates the target value of 1 for the effective reproduction no. required for control. The vertical dashed line indicates the date of report generation.

Confirmed cases and their estimated date of infection in the six regions expected to have the most new confirmed cases


Figure 6: Confirmed cases by date of report (bars) and their estimated date of infection (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates from existing data are shown up to the 2020-05-14 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The vertical dashed line indicates the date of report generation.

Reproduction numbers over time in all regions


Figure 7: Time-varying estimate of the effective reproduction number (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in all regions. Estimates from existing data are shown up to the 2020-05-14 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The horizontal dotted line indicates the target value of 1 for the effective reproduction no. required for control. The vertical dashed line indicates the date of report generation.

Confirmed cases and their estimated date of infection in all regions

Figure 8: Confirmed cases by date of report (bars) and their estimated date of infection (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in all regions. Estimates from existing data are shown up to the 2020-05-14 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The vertical dashed line indicates the date of report generation.

Latest estimates (as of the 2020-05-14)

Table 2: Latest estimates (as of the 2020-05-14) of the number of confirmed cases by date of infection, the effective reproduction number, and the doubling time (when negative this corresponds to the halving time) in each region. The mean and 90% credible interval is shown.
State New confirmed cases by infection date Expected change in daily cases Effective reproduction no. Doubling/halving time (days)
Alabama 418 (339 – 484) Increasing 1.2 (1.1 – 1.3) 14 (9.4 – 31)
Arizona 411 (335 – 480) Likely increasing 1.1 (1 – 1.1) 57 (19 – -63)
Arkansas 200 (161 – 226) Increasing 1.3 (1.1 – 1.4) 11 (7.1 – 25)
California 2486 (2086 – 2874) Increasing 1.2 (1.1 – 1.3) 16 (11 – 25)
Colorado 381 (311 – 447) Likely increasing 1.1 (0.9 – 1.2) 35 (15 – -120)
Connecticut 544 (465 – 616) Unsure 1 (0.9 – 1.1) 160 (29 – -46)
Delaware 176 (142 – 200) Unsure 1 (0.9 – 1.1) -160 (26 – -18)
District of Columbia 160 (126 – 182) Unsure 1.1 (0.9 – 1.2) 33 (13 – -45)
Florida 942 (796 – 1107) Increasing 1.2 (1.1 – 1.2) 18 (12 – 36)
Georgia 863 (703 – 1005) Increasing 1.2 (1.1 – 1.3) 14 (9.5 – 25)
Guam 11 (0 – 21) Increasing 2.4 (0.8 – 3.9) 2.5 (1.3 – 110)
Idaho 41 (22 – 57) Likely increasing 1.2 (0.9 – 1.6) 14 (5.4 – -21)
Illinois 2721 (2295 – 3172) Increasing 1.1 (1 – 1.2) 34 (17 – 2000)
Indiana 665 (560 – 769) Increasing 1.1 (1 – 1.2) 22 (14 – 65)
Iowa 436 (355 – 512) Likely increasing 1.1 (1 – 1.2) 30 (14 – -150)
Kansas 192 (163 – 221) Unsure 1 (0.9 – 1.2) 41 (14 – -46)
Kentucky 175 (149 – 205) Unsure 1 (0.9 – 1.1) -130 (26 – -18)
Louisiana 613 (491 – 737) Increasing 1.2 (1.1 – 1.4) 14 (9 – 29)
Maine 63 (41 – 81) Increasing 1.2 (1 – 1.5) 12 (5.8 – -250)
Maryland 1276 (1071 – 1438) Increasing 1.2 (1.1 – 1.2) 17 (12 – 28)
Massachusetts 1191 (1021 – 1337) Unsure 1 (0.9 – 1.1) 97 (30 – -82)
Michigan 639 (557 – 729) Likely increasing 1.1 (1 – 1.1) 36 (19 – 1500)
Minnesota 813 (691 – 941) Increasing 1.1 (1.1 – 1.2) 19 (12 – 37)
Mississippi 336 (260 – 400) Increasing 1.2 (1 – 1.3) 18 (10 – 71)
Missouri 188 (152 – 223) Likely increasing 1.1 (0.9 – 1.2) 28 (12 – -87)
Nebraska 314 (257 – 370) Unsure 1 (0.9 – 1.2) 44 (17 – -67)
Nevada 127 (103 – 150) Unsure 1.1 (0.9 – 1.2) 91 (16 – -22)
New Hampshire 91 (66 – 110) Unsure 1.1 (0.9 – 1.3) 32 (10 – -25)
New Jersey 1490 (1261 – 1685) Increasing 1.1 (1 – 1.2) 20 (14 – 41)
New Mexico 146 (119 – 168) Unsure 1 (0.9 – 1.1) -1700 (21 – -20)
New York 2027 (1702 – 2305) Unsure 1 (0.9 – 1.1) 160 (32 – -55)
North Carolina 763 (635 – 888) Increasing 1.2 (1.1 – 1.3) 15 (11 – 25)
North Dakota 97 (71 – 116) Increasing 1.2 (1 – 1.4) 13 (6.7 – 200)
Ohio 689 (577 – 830) Increasing 1.1 (1 – 1.2) 21 (12 – 82)
Oklahoma 124 (98 – 144) Likely increasing 1.1 (0.9 – 1.2) 36 (12 – -32)
Oregon 53 (31 – 72) Unsure 1 (0.7 – 1.2) -50 (13 – -8.5)
Pennsylvania 1086 (914 – 1283) Increasing 1.1 (1 – 1.2) 24 (13 – 110)
Puerto Rico 85 (61 – 103) Likely increasing 1.1 (0.9 – 1.3) 23 (8.8 – -35)
Rhode Island 261 (209 – 306) Likely increasing 1.1 (1 – 1.3) 20 (11 – 170)
South Carolina 190 (161 – 219) Likely increasing 1.1 (1 – 1.2) 35 (14 – -64)
South Dakota 86 (60 – 103) Unsure 1.1 (0.8 – 1.3) 33 (9.1 – -20)
Tennessee 446 (350 – 520) Increasing 1.1 (1 – 1.3) 22 (11 – 220)
Texas 1303 (1116 – 1483) Likely increasing 1.1 (1 – 1.1) 80 (26 – -73)
Utah 178 (148 – 203) Likely increasing 1.1 (1 – 1.2) 31 (13 – -68)
Vermont 341 (0 – 35) Likely increasing 3.8 (0.8 – 3.3) -0.11 (1.5 – -22)
Virginia 1086 (917 – 1254) Increasing 1.1 (1 – 1.2) 25 (15 – 88)
Washington 237 (188 – 282) Unsure 1 (0.9 – 1.2) 73 (17 – -30)
West Virginia 54 (34 – 69) Increasing 1.5 (1.1 – 1.8) 6.5 (3.9 – 20)
Wisconsin 511 (401 – 618) Increasing 1.2 (1.1 – 1.4) 13 (8.5 – 25)
Wyoming 26 (6 – 44) Likely increasing 1.3 (0.7 – 1.9) 10 (3.4 – -9.8)

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